U.S. patent application number 11/009140 was filed with the patent office on 2005-06-16 for incandescent lamp having an activating effect.
This patent application is currently assigned to PATENT-TREUHAND-GESELLSCHAFT FUR ELECKTRISCHE GLUHLAMPEN MBH. Invention is credited to Plumeyer, Carsten, Scheyer, Yannick.
Application Number | 20050127836 11/009140 |
Document ID | / |
Family ID | 34638701 |
Filed Date | 2005-06-16 |
United States Patent
Application |
20050127836 |
Kind Code |
A1 |
Plumeyer, Carsten ; et
al. |
June 16, 2005 |
Incandescent lamp having an activating effect
Abstract
The invention relates to an incandescent lamp having an
increased activating effect, in which a greater emission in
absolute terms is achieved in the spectral range having a circadian
effect owing to spectral filtering, on the one hand, and measures
for compensating for the luminous flux losses, on the other hand,
given a lamp output power and luminous efficiency which overall
remain substantially the same. This spectral range has
physiological effects on the human body.
Inventors: |
Plumeyer, Carsten;
(Martinsried, DE) ; Scheyer, Yannick; (Strasbourg,
FR) |
Correspondence
Address: |
OSRAM SYLVANIA INC
100 ENDICOTT STREET
DANVERS
MA
01923
US
|
Assignee: |
PATENT-TREUHAND-GESELLSCHAFT FUR
ELECKTRISCHE GLUHLAMPEN MBH
MUNCHEN
DE
81543
|
Family ID: |
34638701 |
Appl. No.: |
11/009140 |
Filed: |
December 13, 2004 |
Current U.S.
Class: |
313/580 |
Current CPC
Class: |
H01K 1/325 20130101;
H01K 1/32 20130101; H01K 1/50 20130101 |
Class at
Publication: |
313/580 |
International
Class: |
H01K 001/26; H01K
001/42; H01K 001/50; H01K 001/66 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 12, 2003 |
DE |
10358676.8 |
Claims
1. An incandescent lamp which is designed such that it achieves a
minimum luminous efficiency, listed below, dependent on the lamp
output power:
2 Lamp output powers/W Luminous efficiency/lm/W 5-20 5.7 20-33 7.2
33-50 9.2 50-68 10.1 68-88 11.8 88-125 12.6 125-175 13.5 175-250
14.2 250-400 14.4 .gtoreq.400 15.8
and which is characterized by a color filter for filtering the
incandescent lamp light and for increasing the circadian factor to
at least 0.38.
2. The incandescent lamp as claimed in claim 1, in which an
envelope of the incandescent lamp acts as the color filter, in
particular by means of an envelope coating.
3. The incandescent lamp as claimed in claim 2 having an envelope
coating which has Co aluminates having a spinel structure.
4. The incandescent lamp as claimed in claim 1 having an atmosphere
which surrounds an incandescent filament of the incandescent lamp
and has Ar, N.sub.2, Kr and/or Xe in the filling gas.
5. The incandescent lamp as claimed in claim 4, in which the gas
atmosphere surrounding the incandescent filament contains 60-97
vol. % Kr, 0-37 vol. % Ar and 3-40 vol. % N.sub.2.
6. The incandescent lamp as claimed in claim 4 having a filling
pressure of at least 850 mbar.
7. The incandescent lamp as claim 1 having an atmosphere which
surrounds an incandescent filament of the incandescent lamp and
includes a halogen additive.
8. The incandescent lamp as claim 1 having an IR-reflective coating
for the purpose of reflecting IR radiation emitted by an
incandescent filament of the incandescent lamp.
9. The incandescent lamp as claim 1 also in combination with claim
8, whose statistical average life is at most 900 h.
10. The incandescent lamp as claim 1 having a color temperature of
the radiated light of at least 2900 K.
11. The incandescent lamp as claim 1 having a color rendering index
R.sub.a of at least 90.
12. The incandescent lamp as claimed in claim 5 having a filling
pressure of at least 850 mbar.
13. The incandescent lamp as claimed in claim 2 having an
atmosphere which surrounds an incandescent filament of the
incandescent lamp and includes a halogen additive.
14. The incandescent lamp as claimed in claim 3 having an
atmosphere which surrounds an incandescent filament of the
incandescent lamp and includes a halogen additive.
Description
TECHNICAL FIELD
[0001] The present invention relates to an incandescent lamp.
BACKGROUND ART
[0002] Incandescent lamps have long been known per se. They
generate light by means of thermal emission, generally by means of
an incandescent element, for example a metal filament. This is the
historically oldest design for electric lamps which is nevertheless
still of considerable importance partly owing to the low lamp
costs, partly owing to the continuous emission spectrum in
comparison with discharge lamps, and occasionally for reasons of
physical size or for other reasons.
[0003] In principle, incandescent lamps have relatively good color
rendering owing to the continuous emission spectrum, but are
subject to limitations as regards the color temperature, i.e.
specifically as regards the "warmth" or, in contrast, the
"whiteness" of the light. The life of incandescent lamps is
generally limited by the incandescent filament, from which metal is
removed by vaporization, which in the end leads to filament
breakages. Various technologies have been developed to reduce this
problem. In particular, mention may be made here of the halogen
cycle process in the halogen incandescent lamps which is used to
recycle the vaporized metal to the incandescent filament.
[0004] However, in principle it is still the case with incandescent
lamps, even with halogen incandescent lamps, that an increase in
the color temperature, in favor of a whiter light, or an increase
in the luminous efficiency, i.e. the luminous flux (in the unit
lumens (lm)) per unit of electrical output power used (in watts
(W)), by means of the electrical design results in reductions in
life owing to the higher incandescent filament temperatures which
are necessarily associated therewith.
[0005] The known measures, such as the use of different gas
compositions in (conventional) incandescent lamps, the halogen
cycle process in halogen incandescent lamps and other steps known
per se, are in this case, on the other hand, in constant conflict
with cost considerations. As a result of such measures, longer-life
or better (in terms of luminous efficiency) incandescent lamps are
therefore in principle more expensive, with the result that it is
primarily special application fields in which such measures are
taken. For example, halogen incandescent lamps are used in
particular when the color rendering and the whiteness of the light
are of importance. Conventional Kr incandescent lamps, for example,
are still offered more as a niche product owing to their higher
costs.
[0006] Irrespective of this, in recent years it has been shown in
medical investigations that the visible part of the electromagnetic
spectrum also has physiological effects on the human organism. In
particular, it has been shown that the human eye contains receptors
which interact with the control of the hormonal balance of the
sleeping hormone melatonin. These receptors are primarily sensitive
in the blue range, the maximum sensitivity being approximately in
the range from 450-470 nm.
DISCLOSURE OF THE INVENTION
[0007] The invention is based on the technical problem of
specifying an incandescent lamp having improved properties.
[0008] The invention is based on an incandescent lamp which is
designed such that it achieves a minimum rated luminous efficiency,
listed below, dependent on the lamp output power:
1 Lamp output powers/W Luminous efficiency/lm/W 5-20 5.7 20-33 7.2
33-50 9.2 50-68 10.1 68-88 11.8 88-125 12.6 125-175 13.5 175-250
14.2 250-400 14.4 .gtoreq.400 15.8
[0009] This incandescent lamp is characterized by a color filter
for filtering the incandescent lamp light and for increasing the
circadian factor to at least 0.38.
[0010] Preferably used as a basis in the list above are in each
case 2% higher and, particularly preferably, 4% higher luminous
efficiencies. The circadian factor is preferably at least 0.39 and
particularly preferably at least 0.40.
[0011] The basic idea of the invention is to provide an increased
activating effect on the human organism in the case of an
incandescent lamp in comparison with a conventional incandescent
lamp which is comparable in terms of the electrical data. This
effect should take place by increasing the relevant blue component,
which in this case is defined by means of the so-called circadian
factor used as the technical variable. This circadian factor
describes the ratio of the activating component, determined by an
assumed sensitivity curve, of the radiant power to the total
luminous flux. In this case, the luminous flux is the radiant power
evaluated using the spectral visual sensitivity (as regards the
normal impression of brightness). Of concern here is thus the ratio
of two integrals over the radiant power, in one case with the
weighting function of the circadian effect on the activating light
receptors, and in the other case (in the case of luminous flux)
with the spectral brightness sensitivity of the human eye.
[0012] The term "circadian factor" and also the term "luminous
flux" are technical variables used per se. Reference is made to the
definition in the publication by Prof. Dietrich Gall in the journal
"LICHT" [LIGHT], edition 11-12, 2002. However, it should be noted
that the basic physiological mechanisms depend on various
parameters, i.e., for example, the dark-adapted eye reacts
differently from the light-adapted eye. There are also different
economic viewpoints regarding details on the correct circadian
efficiency distribution in the blue spectrum, in particular
depending on the light/dark adaptation, but these will not be
explained in further detail here.
[0013] The invention is demarcated by the fact that the circadian
factor has a value of at least 0.38, preferably 0.39 and
particularly preferably at least 0.40. This is achieved by a color
filter which does not absorb the relevant blue component or absorbs
it more weakly than other spectral components. The color filter
thus generally absorbs predominantly in the yellow range. However,
the invention is not restricted to this filter effect, which in
fact does not increase the activating component in the emission
spectrum at all in absolute terms. Rather, according to the
invention at the same time, a luminous efficiency (i.e. luminous
flux per unit of output power used) is achieved which is at least
comparable with that of a conventional, comparable incandescent
lamp, as is specified above. In this case, a differentiation has
been carried out based on the lamp output power (the so-called
wattages) which also corresponds in conventional incandescent lamps
to the technical facts and boundary conditions. For the specified
limit values, for example 33 W, in each case the higher value shall
be valid.
[0014] Various measures are known to those skilled in the art for
increasing the luminous efficiency which are in principle possible.
For example, it may be expedient to use a filling gas, in
particular Ar, N.sub.2, Kr and Xe, Kr and Xe being particularly
preferred. In particular, mixtures come into consideration which on
the one hand, for reasons of electrode short-circuit strength,
contain some N.sub.2 and, on the other hand, contain a relatively
large amount of Kr. Some Ar may also be provided. The Kr content is
preferably between 60 and 97 vol. %, in particular over 70 or 75
vol. % and, in particular, below 90 or 85 vol. %. The N.sub.2
content in the filling gas is preferably between 3 and 40 vol. %,
inclusive, and preferably below 5 vol. %. The numerical values are
in each case inclusive.
[0015] The Ar content in turn is preferably at most 37 vol. %.
[0016] Further possibilities relate to increased filling pressures
of such or other gas fillings in the incandescent lamp,
specifically preferably over 850, especially over 920 and
advantageously over 980 mbar at room temperature.
[0017] The gas fillings reduce the metal vaporization of the
incandescent filament resulting from impacts, specifically, on the
one hand, depending on the atomic or molecular mass, and, on the
other hand, also depending on the pressure.
[0018] A further preferred possibility consists in using a halogen
incandescent lamp. Although, on the one hand, this increases costs,
on the other hand, the luminous efficiency or life can be
considerably increased in comparison with the fillings described
above. In particular, even using a conventional type of
incandescent lamp, a corresponding, smaller halogen incandescent
lamp can be installed, i.e. a so-called high-volt halogen lamp
within an envelope corresponding to that of a conventional
incandescent lamp. On the one hand, the halogen incandescent lamp
thus has unique technical advantages, and, on the other hand, an
incandescent lamp without a halogen additive likewise has its own
advantages, namely a technically more simple design and reduced
costs.
[0019] Incidentally, the halogen additive does not rule out further
gas additives; in particular, an additional use of Xe may be
advantageous in a halogen lamp.
[0020] A further measure is an infrared-reflecting device in the
incandescent lamp, for example a coating of the bulb or envelope.
This increases the incandescent filament temperature owing to some
of the radiated IR output power being reflected back.
[0021] Finally, as has already been explained initially, in the
case of incandescent lamps the increase in the luminous efficiency
owing to the electrical dimensions of the incandescent filament or
another type of increase in the incandescent filament temperature,
for example owing to the IR-reflective coating, in principle has an
effect on the lamp life. A further optional feature of the
invention is thus to increase the filament temperature and in the
process to take into account a shortening of the lamp life compared
with values for incandescent lamps which are at present
conventional. In addition to the abovementioned measures, or even
without these measures, it is thus possible to increase the
luminous efficiency. Values of at most 900 h, preferably at most
850 h and particularly preferably at most 800 h for average lamp
life are preferred. Although this is a statistical value for a
group of incandescent lamps, when the incandescent lamp types are
designed and tested, the statistical life should be considered to a
certain extent to be a technical parameter, i.e. one which is not
merely known but can also be controlled.
[0022] Although a reduction in the life is in principle considered
to be a disadvantage, in conjunction with the desired activating
effect it may overall be considered to be an advantage to limit the
technical complexity. In principle, the invention should prevent
simple filtering from in the end only concentrating the emission
spectrum on the activating spectral ranges, without there actually
being any real increase therein. Rather, the activating effect
should be increased in absolute terms and, overall, a substantially
"equally bright" or even brighter incandescent lamp should be
produced. This was quantified by the luminous efficiency in the
described manner.
[0023] In this case, the invention also has the advantage that the
lamp not only has a refreshing effect and increases the readiness
of the body and the mind to perform, but is also perceived by the
user to be fresher in subjective terms. This is dependent on the
light which is whiter as a result of the increased blue component
or the reduction of the yellow component which is in principle
excessive in incandescent lamps. It is thus possible to make vision
and in particular reading more contrast-rich and less tiring and to
achieve a fresher and more natural color rendering. The original
functions of the incandescent lamp are thus not only maintained
with the invention but are even improved with an appropriate
design. In particular, color temperatures of at least 2800 K and
color rendering index values R.sub.a of at least 90, preferably 92
and particularly preferably 93 are preferred. The color rendering
index is likewise an introduced variable and denotes the measure
for the correspondence of the surface color with its appearance and
the illumination by means of the corresponding lamp. For this
purpose, color shifts are determined on the basis of eight test
colors standardized in the German industrial standard DIN 6169, and
a corresponding index value is calculated. A theoretical, optimal
lamp achieves a value of R.sub.a=100.
[0024] The abovementioned color filter may have a wide variety of
designs, in particular even a separate lamp component or a gaseous
addition. However, preferred are color filter properties of the
lamp bulb and, if provided, preferably of the lamp envelope owing
to coatings, colorations or dopings. In addition to doping the bulb
glass with Nd or dyes in the blue range contained in the glass,
coatings using pigments are also conceivable. Particularly
preferred are color filters which at least contain, inter alia, a
coating with cobalt aluminates having a spinel structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The invention will be explained in more detail below with
reference to exemplary embodiments, it being possible for the
disclosed individual features also to be pertinent to the invention
in other combinations.
[0026] FIG. 1 shows a schematic illustration of an incandescent
lamp according to the invention.
[0027] FIG. 2 shows a schematic illustration of a halogen
incandescent lamp according to the invention as a second exemplary
embodiment.
[0028] FIGS. 3a, b, c show the principle of the invention using
three spectral graphs.
BEST MODE FOR CARRYING OUT THE INVENTION
[0029] FIG. 1 is an outline illustration of an incandescent lamp
according to the invention. The incandescent lamp has an
incandescent filament holder 1 and power supply lines 5 within an
outer glass bulb 2. A twin-coil filament wire 4, for example, which
is held by the incandescent filament holders 1, is stretched in the
form of a luminous element between the power supply lines 5. The
power supply lines 5 are sealed into the glass in a manner known
per se and passed out and connected, within a conventional screw
base 6, to the contacts of said screw base 6, as is illustrated in
FIG. 1 by dashed lines.
[0030] When the incandescent lamp is screwed into a fitting and has
voltage applied to it, a current flows through the incandescent
filament 4, causes the latter to incandesce and results in a
thermal light emission.
[0031] According to the invention, the glass bulb 2 has, in this
first exemplary embodiment, an electrostatic powder coating with
cobalt aluminate pigments having a spinel structure applied on the
inside, which markedly reduces the yellow component of the emitted
light. In this exemplary embodiment, 12% by weight cobalt
aluminates having a spinel structure are used which are embedded in
88% by weight highly disperse silica powder. For details, reference
is made to the explanation for FIG. 3. In the present case, the
circadian factor increases in the process by approximately 15% to a
value of approximately 0.41 in the case of a 60 W incandescent
lamp. Without further measures being taken, however, the luminous
efficiency would be significantly reduced, to be precise in this
example by approximately 20%.
[0032] The incandescent lamp according to the invention therefore
also envisages a mixture of 80 vol. % Kr and 20 vol. % of a mixture
of 85 vol. % Ar and 15 vol. % N.sub.2 as the gas filling. The
filling pressure is 1000 mbar. These measures make it possible to
increase the luminous flux in turn by approximately 12%. In
addition, the filament temperature is increased to such an extent
that the average life expectancy of approximately 1000 h is now
reduced to approximately 700 h. This makes it possible to increase
the luminous flux by a further 8%, with the result that the
luminous flux approximately corresponds to that of an unfiltered,
conventional 60 W incandescent lamp. In addition, an IR-reflecting
coating of the bulb 2 may optionally be used.
[0033] Otherwise, this example uses a conventional incandescent
lamp having a so-called A bulb and a so-called E 27 base, designed
for an effective operating voltage of 230 V.
[0034] The color temperature in this example is 2923 K given a
color rendering index of R.sub.a=94.
[0035] Overall, the circadian factor can thus be increased by
approximately 15% whilst the luminous efficiency remains the
same.
[0036] In the example illustrated, the actual lamp output power was
61.6 W and produced a luminous flux of 655 lm.
[0037] Of course, other bulb and base forms are also
conceivable.
[0038] The incandescent lamp according to the invention thus has a
refreshing and activating effect on the human body and can
influence the biorhythm. This takes place by means of inhibition of
the melatonin formation by an increased light radiation in the
region of approximately 450 nm. In addition, the lamp is perceived
to be pleasant and comfortable owing to the whiter light which has
a fresher effect and owing to the improved color rending.
[0039] FIG. 2 shows an alternative example in which the
conventional incandescent filament 4 from FIG. 1 has been replaced
by a high-volt halogen lamp which is conventional per se.
Specifically, in FIG. 2 a high-volt halogen lamp 7 is inserted into
the bulb 2 shown in FIG. 1 and has a dedicated small bulb for the
purpose of reducing the gas filling volume. The envelope 2 is
coated as already explained with reference to FIG. 1. In this case,
the luminous efficiency can be increased using halogen technology.
In addition, it is naturally also possible for further measures to
be taken to increase the luminous efficiency as compared with that
of a halogen incandescent lamp, for example at the expense of the
life.
[0040] Other exemplary embodiments are naturally also conceivable
in which, for example, low-volt halogen lamps have a corresponding
filtering coating for a lamp or envelope.
[0041] In the case of reflector lamps having cover disks set in
front it is possible to achieve comparable effects by using special
filter disks.
[0042] FIGS. 3a, b, c explain the principle of the invention using
three spectral graphs a, b and c, in which the radiation intensity
of the lamps (in relative units) is plotted in nm as a function of
the wavelength of the radiation. The first graph a shows, using the
continuous curve, the radiation intensity of a conventional 60 W
incandescent lamp which corresponds to the incandescent lamp shown
in FIG. 1, apart from the measures according to the invention. This
relates to a part of the thermal emission which is in the visible
wavelength range. The curve is similar to a section of the
Planckian locus for the so-called black body radiator, but the
short-wave radiation is increased slightly when tungsten is used as
the incandescent filament material.
[0043] The dashed curve shows the product of this continuous curve
with the relative sensitivity of the blue-sensitive receptors
(already mentioned many times) of the human eye which are partly
responsible for controlling the melatonin generation. The basic
sensitivity curve, as can be seen, lies in the blue spectral range.
The maximum sensitivity (100%) corresponds to points at which it
comes into contact with the continuous curve. The details are
dependent in particular on the light/dark adaptation of the eye and
are not explained here specifically. The dashed curve thus only has
qualitative significance.
[0044] The dash-dotted curve shows the product of the continuous
curve with the spectral brightness sensitivity of the human eye,
and thus relates to the usual powers of vision. The brightness
sensitivity has a maximum of approximately 555 nm, i.e. in the
green range. An integral over the dash-dotted curve would give the
luminous flux of the lamp.
[0045] Graph a thus shows that a conventional incandescent lamp
only has small components having a circadian effect and, relative
thereto, even relatively large brightness-relevant components, but
primarily a pronounced yellow and red range, owing to the typical
spectral distribution in the thermal emission.
[0046] Graph b shows the curves from graph a, the continuous curve
being dotted in this case. The continuous line in graph b
corresponds to the incandescent lamp emission following filtering
according to the invention. It can be seen that the filtering
filters off hardly any spectral power in the range having a
circadian effect, but shows a marked filtering effect in the range
between 500 and 700 nm. In addition to the in turn relatively
lesser filtering effect in the range between 700 and 800 nm, it
should be mentioned that there is also the objective of keeping an
overall white impression so that there are no faults in the color
of the lamp. It can be seen that the dash-dotted curve is lower and
the lamp is thus less bright.
[0047] Graph c is a qualitative illustration of graph b, but the
continuous curve is vertically higher. In this case, the above
described compensation of the luminous flux loss has been taken
into account. In graph c, the dotted and the continuous lines thus
substantially show the same luminous flux and thus essentially the
same luminous efficiency (given a lamp output power which has
remained the same). In other words: the integral of the dash-dotted
curve over the visible range is approximately the same in both
cases. The incandescent lamp according to the invention shown in
FIG. 1 corresponds to this continuous line. The dashed line which
is higher in this case in comparison with graphs a and b shows
that, as a result, the circadian spectral range has increased in
absolute terms.
* * * * *